Elevator safety device.



I. H. VENN, ELEVATOR SA FETY DEVICE.

APPLICATION FILED FEB- 14; 1914,

1 Patented Oct. 9, 191.7.

2 SHEETS -SHEET I.

I JI I H l l l l l. H. VEN N. I ELEVATOR SAFETYDEVICE,

APPLICATION mzp ran. :4. m4.-

Patented; Oct. 9, 1917.

2 SHEETS-SHEET 2- INVE/VTUH:

WITNESSES.-

A OHNE UNITED s AEs ra'rnnr onnron.

ISAAC IL VENN, or YONKERS, YORK, easter ies. rro orls. erevaroa Q M Y.or JERSEY CITY, NEW master A ,coarqnermlr or essy.

' ELEVATOR sar'nrr EV-Ion.

Specification of Letters Patent.

. Pat nted ce 9., .91

Applieation filed February 1'4, 1914., Serial No. 818,7;95.

citizen of the United States, residing in Yonkers, in the county ofWestchester and State of New. York, have invented a new and usefulImprovement in Elevator Safety Devices, of which the following is aspecification. V Y

My invention relates to safety devices for elevators, and has for anobject the provision of means for applying a brake to an elevator car orits counterbalance weight, or both, in case of emergency, said brakeautomatically effecting a retarding action in accordance with the load.

-A further object of the invention is the provision of an elevatorsafety device which may be automatically operated with varying degreesof power depending upon condi: tions. V Other objects of the inventionwill appear hereinafter, the novel combinations of elements beingpointed out in the appended claims. I

In the accompanying drawings, Figure 1 represents diagrammatically anelevator installation containing an embodiment of my invention; Fig. 2is anenlarged detail view of the safety device as applied to theelevator car; Fig. 3 is a sectional end view of the safety plank; Fig. 4is a view showing a modification. V Similar parts are designated by likereference characters in all of the figures.

Referring to Figs. 1, 2 and 3, an elevator car 0 is suspended by a cableor cables A which are associated with a drivingsheave M and idler sheaveI, and are secured to a counterbalance weight W. The usual guide railsfor the car and counterbalance weight are designated by B. Associatedwith the car and counterbalance weight aresafety planks S, S, which notonly embodynovjel features in themselves, but also involve a novelty inthe manner in which they are suspended and in which they. operate. 7 Forexample, the safety plank S under the car, is suspended from either endby means of cables 1, l, which may lead up' the side of the car and beconnected to a, yoke? as shown. The latter isconnected to a cable 3,which leads over. the guide sheaves 4, 4, and is secured to thecounterbalance weight W. The safety plank Swunder the counter-V i t susp ree the ca le w iche e n t d t yok 6- h a t is connected to a cable7 which leads over h g de sheaves 8,, 8, and is secured to, the top ofthe car. With this arrangement of the safety planks S, .S, the samenormally will move up and down the hatchway with the car andcounterweight, while under C n i ns h y'may have a la e movementthereto, respectively. The cables 3'ancl7 f-ro nwhich the car andcounter? weight safety planks S, S, are suspended,

respectively, are adapted to be gripped by means of the clamps Qand '10,respectively, both of Whichclamps are connected to a rod 11, under thecontrol of the speed governor G. The governor G may be driven from anyconvenient part ofthe elevator ap.p ar.a'

tus such as byasprocket chain or. belt 12 associated with the idlersheave I so that the governor rotate at a speed in accordance with thatof the elevator car. Fig.

4 illustrates a common method of driving the governor direct from thecar.

The safety planks S, S are substantially similartofle'ach other, andeach comprises .a pair of channels 12, 12 (see Figs. and to which aresecnred at either end apair .of massive 1 steel: blocks 13 .(Fig. 3)each of which is slotted out so as to receiventhe guiderail web'and awedge 14. "The latter is provided with a: head 19 which normallyrests'on top-of jthe blockfl3 and isfmaintain'ed .outof contact with therail bymeans of a spring 17 and stud 16,-whichlatter is.

secured ,to the wed e and adapted :to slide in a groove 18 infile block13 and one of the channelsl2. To each wedge 14,14is pivoted 'a lever20fulc'rumed at'21 to a bracket 22 carried by the safety plank channels.The pivotal connection between the levers and each wedge is providedwith a slight amount ofside play so as.to prevent cramping therebetween.The inner ends of the levers 20 on the car safety are slotted at 25 toreceivea pin 26 carried by a rod 27 extending through the floor of thecar and Pr v ded h a fo Pi 28,- A sp n 29 tends to move vthe rod 27 andinner ends of the levers 20 upwardlyand' to depress the wedges 14, 14.To the bottom :of the car are secured a pair of plungers 13 1, 31,;thelower ends of which are within a short dis.- tance of the plunger seats30, 30,, carried by the levers 20, -20. Theplun'gers 31, ,31, areenlarged at, 32, 32 ,where they pass through the safety plank, and theseenlarged portions are embraced by channels 35, 35, which act as a meansfor steadying the safety plank. Plates 3%, 34, are secured to the top ofthe safety plank and loosely surround the plungers so as to permit arelative movement of the car and safety plank within limits, but theseplates will be engaged by the enlarged portions 32, 32 of the plungersin case the cables 1, 1, should part and thus prevent the safety plankfrom falling down the hatchway.

Whereas the levers 20, 20, are shown pivoted by pins 21, 21, to thecenter of the brackets 22, I provide other holes 23, 23, in each of thebrackets and levers so that the pins 21, 21, may be removed from theirpresent location and inserted in any one of the holes 23, 23. By thisarrangement I provide a convenient means for varying the fulcrum of thelevers 20 and thereby varying the power with whichthe wedges will engagethe guide rails.

The operation of the safety device depends upon a relative movementbetween the car or counterbalance weight and its respective safetyplank. This relative movement may be brought about in any one of severalways, namely, by manual means un der the control of the operator; byautomatic speed controlled means; and automatically upon breakage of thehoisting cable or cables without regard to the speed.

In order to effect the operation of the car safety device by manualmeans, the operator depresses the rod 27 by means of the foot pedal 28or by hand, and in so doing the levers 20 are simultaneosuly rocked upontheir pivots 21, 21, and the wedges 1 1, 14, moved upwardly and intoclose engagement with the guide rails B. The safety plank S is nowretarded in its further movement in a downward direction and thedescending oar carries the plungers 31, 31, into engagement with thelevers 20, 20, and thereby forces the wedges further into engagementwith the guide rails. If the pivot or fulcrum 21, 21, of the levers 20,20, is midway between the plunger seats 30, 30, and the points ofconnection between the levers and wedges, the latter will. be forcedupwardly with a pressure substantially equal to the combined weight ofthe car and its load, whereas if the pivot or fulcrum 21 of each lever20 be located in one of the holes 23 nearer the wedge than the plungerseat 30, the upward pressure on the wedges will be greater than thecombined weights of the car and its load by an amount dependent upon therelative length of the lever arms. Should the pivot or fulcrum belocated at one of the holes 23 nearest the plunger seat 30, the upwardpressure on the wedges will be less than the combined weights of the carand its load.

In any event, the retardation of the car will be proportional to theload.

The operation of the safety device by speed controlled means is effectedby the governor G in the following manner. when the car is operating upor down within normal speed limits, the governor G remains inactive andthe cables S and 7 pass freely over their respective guide sheaves 4 and8. If the car be descending, and for some reason its speed should becomeexcessive, the governor balls will fly outwardly and depress thegovernor rod 11 and thereby actuate the eccentric clamps 9 and 10. Theclamp 9 will immediatelv grasp the cable 3 and retard its furthermovement there through. Now, since the cable 3 suspends the safety plankS under the car. it follows that the latter will be arrested in its downward. movement, and the descending car will settle upon the levers 20,20, which will at once raise the wedges 14 into engagement with theguide rails, and the car will be graduallv arrested inaccordance withthe load and finally stopped, the safety plank being carried downwardlywith the car. It will be observed that the safety device on thecounterbalance weight will not be operated bv the governor with adescending car, since the governor clamp .10 merely places a brakingaction on thecable 7, and as the counterbalance weight is moving upwardly at this time there will be no rela tive motion between thecounterweight and its corresponding safety plank.

In the event of excessive speed with an ascending car, the governorclamp 10 will restrain the cable 7 which supports the counterweightsafety plank, and the latter will be retarded, whereupon thecounterweight will settle upon the levers of its safety plank and thecorresponding wedges will operate to retard and arrest thecounterweight. If the descending car is stopped. by its correspondingsafety device, the driving traction between the sheave M and thehoisting cable becomes destroyed and the counterweight will not befurther raised even though the sheave M continue to be driven. The samething takes place when the counterweight safety operates with anascending car. If the traction driving sheave be replaced by a windingdrum and the car be arrested by its safety plank, there will be nodanger of the counterweight being hoisted to the top of the hatchway,since the unbalanced weight of the counterweight will be in excess ofthe power of the hoisting engine or motor and the latter will bestalled. The same thing will take place if the car he ascending, to wit,the counterweight will be arrested by its safety plank, and theunbalanced load represented by the loaded .car will stall the motor.

It will be observed that I provide a stop 36 in connection with thegovernor Gr, the purpose of which is to prevent the clamps 9 and 10frompositively locking the corresponding cables 3 and 7 Some arrangementof this kind is desirable since it ob-.

car or counterweight, as the case may be, to

settle on the said planks and actuatethe wedges. Other types of clampsmay be used if desired other than the eccentric type as illustrated, butI prefer to use a clamp whose power may be predetermined so as to effecta known retardation of the cables '3 and 7 of which there are manykinds, the ones herein shown being merely by way of example. i

.As before pointed out, the safety device is arranged to be operated notonly by the operator and also automatically in the event of excessivespeed, but also incase the hoisting cable or cables part, regardless ofwhether the carbe in motion or not. This. feature in itself is of. thegreatest impor-' tance sinceit insures thatin case the hoisting cable orcables part, both the car and counterweight immediately become locked tothe safety device doesnot come into effectiveoperation until after thecar has fallen a substantial distance and moreover is falling at a veryhigh rate of speed. If the cables should part while the car were nearthe top of the hatchway, the safety clamps would have a chance to stopthe car before it reached the bottom of the well, but if the cablesshould part with the car near the bottom of the well, the safetyidevicewould not have an opportunity materially to check the speed of the carbefore it struck the bottom;

The counterweight in the meantime suffers a free. fall and in alllikelihood-will do;

great damage.

By reason of myinvention I am enabled. to arrest both the carlandcounterweight 'in' case the hoisting cables part before either.

the car or counterweight'has had time to fall more than a veryfew-inches at'most,

so that all danger of a free 'fall athigh speed is absolutely done awaywithf Y Referring to Fig. 1, let us suppose that the car is at rest, andthe hoistingcable or cablesA should part. The car and counterweight arenow free to fall and will at once attempt to do so. As the counterweightmoves downwardly it raises the safety plank S under thecar, while at thesame time the car, in moving downwardly, raises the safety plank S underthe counterweight, hence it will be seen that the car and itssafetyplank are'carried in opposite directions toward eachother whilethe counterweight and its safety'plank are simultaneouslymoving inopposite directions toward each other. By reason of this operation thewedges on both of the safety planks will almost instantly be applied andboth car and counterweight will be arrested before eitherv has movedmore than an inch or two 'at the most and consequently long beforeeither the car or counterweight have had time to attain even a moderatespeed in a downward direction.

It will further be observed that the retarding power of the-wedges isgreater in case the hoisting cables break than would be: the case if thesafety device were operated by hand or by the governor. In the lattercase the safety plank under the car isarrested by theg'overn'or clamp,and the car settling down on the levers 20, 20, applies the wedges witha power dependingupon the weight of the car and its load and also: uponthe retardation of the safety plank inducedby the governorclamp. In casethe hoisting cable or cables break, the total; power applied to the carsafety wedges is that due not only to the weight of the car and its loadacting through the levers 20,

20, but also to the added power due to the,

upward movement of the car safety plank, which upward movement will beeffected by a considerable part of the weight of the counterbalanceweight. To better illustrate the action of the car safety under theseconditions, we may assume that the car and its load weighs 5000 lbs,while the counterweight weighs 4500 lbs.-. If the hoisting cable orcables should break, the car will set tleon the levers 20, 20 with apressureof 5000 lbs. while the counterweight ispulling up: on the carsafety plank with a force of4500 lbs., ignoring for the timebeing theaction of, the a'counter'weight safety. The total force exerted on thelevers .20, 20 willthere' fore be,;we may say, 5000 lbs. +4500 lbs,- or9000 lbs; The same thing is taking placein connection with thecounterweight, andits. safety device, and the; ultimate resultwillbethat the braking power of thewedge sis-far in exc'ess'of what it wouldi138: in "case the safety device were actuatedby the gov-- ernor underexcess, speed conditions. WVhile the action of the 'safety'wedges under;the

of the safety wedges under the car will notv permit the entire weight ofthe car and its load to be available to raise the safety plank under thecounterwelght, nevertheless a large portion of these weights isavailable to and counterweight will not be greater thanthat required tobring the unbalanced load to rest. This case calls for a safety deviceof moderate power. On the other hand, in case the hoisting cables part,the power of the safety devices will automatically be greatly increasedso as to take care of the unbalanced car and counterweight which nowrepresent a dead load. By this arrange ment the action of the safetywhen operated by hand or automatically by the governor will be moderateand in proportion to the load, so that the car will always comegradually and easily to a stop whatever the load maybe, and hence allshocks and jars to the elevator apparatus or discomfort to thepassengers is avoided. When the hoisting cables part, the action of thesafety device in stopping the car and counterweight is so extremelyrapid that there can be no possibility of the car attaining anyappreciable speed and hence there can be no shock or jar,notwithstanding the great power of the safety at this time.

lVhereas the parting of the hoisting cables of any elevator installationis but a very remote possibility when the apparatus is properlyinspected from time to time, the likelihood of the car attaining anexcessive speed from some disarrangement of its hoisting machinery, orin the case of an electric elevator, from some defective electric switchor false operation in the controlling circuits, or otherwise, is muchmore likely to occur and frequently does. In the generally accepted typeof elevator safety device, the braking or retarding action of the samemust be such that the car will be arrested smoothly and without shock orjar when the maasee the hatchway with little checking of speed until itstrikes the bottom of the shaft with great force, which of course, ismost likely to result in serious damage both to the car and its load ofpassengers.

By reason of my invention I am enabled to apply a braking action toeither the car, counterweight, or both, which shall automatically be inproportion to the load. If the load be light, the braking action will becorrespondingly gentle; if the load be heavy, the braking action will becorrespondingly powerful. In each case the retarding action of thesafety device is automatically increased or decreased in proportion asthe load increases or decreases, the arresting of the car being effectedgradually and gently without any possibility of shock or ar andregardless of load conditions. Furthermore since the retarding power ofmy safety device is proportional to the load, it follows that for agiven speed the elevator car may always be stopped within apredetermined distance regardless of the load.

The pitch of the wedges 141-, should preferably be such that under nocircumstances can the wedges be iminovably jammed be-' tween the guiderails and the steel blocks 13. The relative length of the arms of thelevers 20 as determined by the position of the adjustable fulcrum 21with respect to the plunger seat 30 and pivotal connection between thelever and the wedge, may best be determined by experiment so that the upward pressure on the wedges will not be excessive. If desired, the pitchof the wedges and the length of the lever arms may be so proportionedthat the resultant brake action will be just sufficient to bring the carand counterweight to a very slow speed so that the car will not bebrought to rest, but may slowly slide down the guide rails and gentlycome to rest at the bottom of the hatchway. This feature is not found inelevator safety devices in present day use and is of great practicalvalue. For example suppose an elevator be equipped with the usual safetydevice and a fire should break out in a building. The elevator, underthese conditions would be operated as rapidly as possible and at thesame time would in all likelihood be heavily overloaded on each downwardtrip. This condition is most favorable for excessive speed, and thisspeed might easily rise above that at which the speed governor is set tooperate. Under these conditions the safety device will act and the carwill be locked in the hatchway against movement, and the entire load ofpassengers consumed without any possibility of saving themselves or ofreceiving aid from an outside source. By reason of my invention thesafety devices could be so adjustedthat the elevator car would not bebrought to rest at an intermediate point in the hatchway, but would begradually retarded to a slow speed regardless of the load and thenpermitted gently to slide down to the basement landing, where it wouldbottom without damage to itself or its live load.

It will be observed that the wedges will always operate simultaneouslydue to the slot and pin connection between the levers 20, 20, so thatthe brake action on each side of the car or counterweight is the sameand comes into effect at the same time, so that there will never be atendency for the car or counterweight to cant.

It may further be observed that the safety device is self resetting. Forexample: If the car be arrested by the manual operation of the safetydevice or automatically due to excessive speed in a downward direction,the hoisting motor may be reversed and the car lifted out of engagementwith the levers I of its safety plank. The spring 29 will in allprobability retract the wedges to their normal inactive position, but ifthis spring should lack the necessary power, a slight upward pull on thepedal 28 will efiect the desired result. In like manner, if the safetydevice on the counterweight be operated with an ascending car, and thehoisting motor be reversed, the spring associated with the counterweightsafety levers 20, 20 will assist in returning the wedges to normalposition out of engagement with the guide rails.

I desire not to be limited to the precise construction and arrangementof parts herein disclosed, since it is obvious that various changes andmodifications could readily be made by one skilled in the art withoutdeparting from the spirit and scope of the invention.

What I claim is e 1. The combination with a car and con terweight andtheir respective guide rails, of a cable connecting the car andcounterweight, a safety device under the car and counterweight, separatecables connected to the car and to the counterweight, respectively, forsuspending each safety device independent of the first named cableconnecting the car and counterweight and of each other, and means forefiecting the operation of said safety devices upon an abnormal relativebodily movement between the car and counterweight.

' 2. The combination with a car and counterweight and their respectiveguide rails, of a hoisting cable connecting the car and counterweight, asafety device under the car and counterweight, respectively, means forsuspending said safety devices independently of said hoisting cable andof each other, and means operative upon breakage of the hoisting cablefor effecting a movement toward each other of the car and its safetydevice and the counterweight and its safety device to effect the suddenactuation of both of said safety devices.

3. The combination with a car and counterweight and their respectiveguide rails, of a hoisting cable connecting the car and counterweight, asafety device under the car and counterweight respectively, means forsuspending said safety devices independently of said hoisting cable andof each other, and automatic means operative upon excessive car speedfor effecting a movement toward each other of the car and its safetydevice and the counterweight and its safety device to effect theactuation of said safety devices.

4;. The combination with a car and counterweight,of safety devicescarried by the said car and counterweight, speed controlled means foreffecting the operation of the safeties, a connection between the safetyon the counterweight and the car, and an independent connection betweenthe safety in the car and the counterweight, the car increasing theapplication of the safety of the counterweight through said connection,and the counterweight increasing the application of the safety to thecar through the other connection.

5. The combination with a car and counterweight, of a cable connectingthe car and counterweight, a safety for the counterweight, a separatesafety for the car, a cable connecting the car with the safety on thecounterweight, another cable connecting the safety on the car to thecounterweight, these cables being independent of the first named cable,and adapted to apply the said safeties simultaneously to the car andcounterweight.

6. The combination with a car and counterweight, of a cable connectingthe car and counterweight, safety devices for the car and counterweight,a cable connecting the counterweight safety and car direct, anothercable connecting the car safety and counterweight direct, and speedcontrolled means for operating one or the other ofsaid safeties in bothdirections of travel of the car.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

ISAAC H. VENN.

Witnesses:

Gnonen D. Rosn,

SCHUYLER PHILLIPS.

copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

